Conventionally, endoscope devices for irradiating illumination light and obtaining endoscopic images within body cavities have been widely used. With such endoscope devices, an electronic endoscope has image-pickup means for introducing an illumination light from a light source device into the body cavity using a light guide or the like and captures an image of the subject with the return light, and image-pickup signals from the image-pickup means are subjected to signal processing with a video processor, thereby displaying an endoscopic image on an observation monitor, so that an observation portion such as an affected area or the like is observed.
In the event of performing normal living body tissue observation with an endoscope device, white light of the visible light region is emitted with a light source device, frame sequence light is irradiated on the subject via, for example, a rotating filter such as RGB or the like, and the return light from this frame sequence light is synchronized with a video processor, so as to obtain a color image, or a color chip is disposed at the front face of the image-pickup surface of the image-pickup means of the endoscope and an image is captured by dividing the return light from white light into RGB, and image processing is performed at the video processor, thereby obtaining a color image.
On the other hand, the absorption properties and scattering properties of the light at the living body tissue differ according to the wavelength of the irradiated light, so in recent years, various types of infrared light endoscope devices, which are capable of observing the tissues at the deep part of the living body tissue by irradiating infrared light on the living body tissue as the illumination light, for example, are proposed.
However, with living body tissue diagnosis, while the deep tissue information near the surface of the tissue is also an important object of observation, with the above-described infrared light endoscope devices, only the deep tissue information deeper than the tissue surface can be obtained.
Also, in the event of irradiating white light on the living body tissue as RGB frame sequential light from a rotating filter, the wavelength regions thereof differ, so while image-pickup signals from light of each color has different deep part tissue information near the tissue surface of the living body tissue, but generally, the white light is separated into an RGB light with each of the wavelength regions overlapping, in order to obtain a more natural color image for the endoscopic image by the RGB frame sequential light.
That is, with overlapped RGB light, there is a problem that desired deep tissue information near the surface of the tissue of the living body tissue cannot be readily recognized, since a broad range of the deep tissue information is taken into the image-pickup signals of the light of each wavelength region.
The present invention has been made in the light of the above-described situation, and first, it is an object thereof to provide an endoscope device and light source device capable of obtaining tissue information of a desired depth near the tissue surface of the living body tissue.
Also, it is a second object of the present invention to provide an endoscope device whereby tissue information of a desired depth near the tissue surface of the living body tissue can be separated and visually recognized.